Long time a go i build loudspeakers based on Seas P17 RE TVFC/COAX elements. Closed enclosure 12 litres net volume.
From the archives i found schematics for the crossover network. Since on that time my knowledge of loudspeaker design was very limited, the crossover is designed using ”Stetson”-method. It was simulated using ltspice (no acoustical measurements etc).
The speaker sounded quite thin and after i got some measurement equipment the reason was found to be baffle-step (never hear of such thing before). So i added 2.2mH inductor and 9 ohm parallel resistor (looked from excellent book The Loudspeaker Design Cookbook).